<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        body {
            border-style: dotted;
            border-color: gray;
        }

        .underline {
            text-decoration: underline;
        }

        .strike {
            text-decoration: line-through;
            text-decoration-color: gray;
            text-decoration-thickness: 2px;
        }

        .overline {
            text-decoration: overline;
            text-decoration-color: gray;
            text-decoration-thickness: 2px;
        }
    </style>
</head>
<body>
<p class="underline">Привет, мир!</p>
<p class="strike">Привет, мир!</p>
<p class="overline">Привет, мир!</p>
</body>
</html>